ntdll.dll is a module that contains NT system functions... I would make sure that all software e.g. anti-virus + other watch dogs + monitoring software etc... [many apps use this DLL.... BES also ]... are quited before running the installer... sometimes there are conflicts with other programs...

__________________Native but 4th class citizen of a nation governed by idiots who import congestions & contention.

I had this same problem upgrading from 4.0sp3hf4 to 4.1. To correct this I had to reinstall the 4.0 code then run the 4.1 install.

The same "install the old 4.0" code worked for me, too.

Once I got the 4.1SP2 package to run, I also ran into an issue towards the end of the installation where the install program claimed not to have permissions to write files to c:\Program Files\Common Files\Research In Motion\AppLoader.

The folder permissions were all fine. The only way I could get around that one was to drag each preexisting file out of the folder each time the installer complained about permissions, at which point it merrily wrote the file to the very same folder that it claimed not to have permissions to do so.

I've never had a dull production BES upgrade, only the test box upgrades go smooth as silk.

Couldn't upgrade from 3.x to 4.x, setup.exe wouldn't load. Was told it could be multihomed server problem, but it wasn't it because I had only one NIC.

I managed to resolve this problem the very simple way: first, I updated my
3.x server with the latest service pack (I think it was 7 or something like that), then restarted server and ran setup again. This time setup appeared and the upgrade went on flawlessly.